This application relates to portable electronic devices, and more particularly to a barcode scanner and communications module for use with such devices.
In the past, various optical readers and scanning systems have been developed for reading barcode symbols appearing on a label or surface of an article. Generally, a barcode symbol is a coded pattern of indicia comprised of a series of bars of various widths separated by spaces of various widths, the bars and spaces having different light-reflecting characteristics. Barcode scanning systems electro-optically transform the graphic indicia into electrical signals. The system decodes these signals into alpha-numerical characters that provide some information about the article. Such characters are typically represented in digital form, and are used as input to processing systems associated with applications such as point-of-sale and inventory control. Scanning systems of this general type are well known in the art and have been disclosed, for example, in U.S. Pat. Nos. 4,251,798, 4,360,798, 4,369,361, 4,387,297, 4,409,470 and 4,460,120, all assigned to the assignee of the present invention.
Such scanning systems generally include a hand-held laser scanning unit. The scanning unit is configured to enable a user to aim it at a barcode pattern and emit a beam of light. The light beam is optically modified, typically by a lens or mirror, to form a beam spot of a certain size at a target distance. Preferably, the beam spot size at the target distance is approximately the same as the minimum width between regions of different light reflectivity, (i.e., the bars and spaces of the symbol).
Barcode scanning systems typically include a sensor such as a photodetector, that detects light scattered back from the barcode pattern. The photodetector is usually positioned in the scanner such that it has a field of view which extends across and slightly past a symbol within the pattern. A portion of the light that is reflected off the symbol is acquired and converted into an electrical signal. Subsequently, electronic circuitry or software converts the electrical signal into a digital representation of the data contained therein. For example, the analog electrical signal from the photodetector may be converted into a pulse width modulated digital signal, with the widths corresponding to the physical widths of the bars and spaces. Such a signal is then decoded according to the appropriate protocol into a desired information format.
Currently, however, many portable electronic products such as notebook computers, personal digital assistants (PDAs), cellular telephones, and calculators do not have barcode scanners included as one of their peripheral devices. One reason for this is lack of space on such devices for an independent barcode scanning module. If, however, a barcode scanner could be integrated alongside an existing peripheral such as an Infrared Data Association (IrDA) interface, without substantially increasing the peripheral""s volume, the functionality of such portable electronic devices could be advantageously increased.
It would therefore be desirable to provide an integrated communication and barcode scanning module for portable electronic devices.
It is therefore an object of the present invention to provide an integrated communication and barcode scanning module for portable electronic devices.
This and other objects of the present invention are accomplished by providing an integrated optical communication and barcode scanning module for portable electronic devices. The module is generally capable of two mutually exclusive modes of operation, a data acquisition mode and a communications mode. In the communications mode, the module may be configured to function as an IrDA communications interface. In the data acquisition mode, the module is configured to function as a barcode scanner.
The integrated module may include a scanning mirror, a light emitting diode (LED), a receiver photodiode, a power-monitoring photodiode, and a semiconductor laser diode. In the communications mode, the module pulses the LED ON and OFF to transmit light signals. Incoming light signals are received by the scanning mirror and reflected off of a the collection optics in a canopy assembly located above the sensing components and onto the receiver photodiode. The receiver photodiode converts the light signals into electrical signals which are subsequently processed and converted into digital information. A preferred embodiment of the collection optics is a parabolic mirror, but other optical surfaces such as spherical or aspheric mirrors are acceptable.
In the data acquisition mode, optical communication is temporarily disabled and the components required for barcode scanning are turned ON. This includes actuating the scanning mirror, and activating the laser diode and power-monitoring photodiode. Light signals generated by the laser diode are reflected off of a focusing mirror that is recessed from the parabolic mirror and behind and aperture and onto a nearby barcode pattern. A portion of the light signal is reflected back onto the parabolic mirror and is directed to the receiver photodiode. Circuitry within the integrated module converts the light signals into electrical signals which are subsequently processed into digital information.
A portion of the light signal emitted by the laser diode is deflected from a section of the parabolic mirror around the aperture toward the power-monitoring photodiode. This is done in order to sense the intensity of the emitted light signal. The intensity of the light signal is monitored to ensure that it is within acceptable operating parameters. The module is preferably constructed such that it fits into a space roughly equivalent to that of a conventional IrDA port.
In an alternative embodiment, the barcode scanner could also be implemented using an infrared wavelength. To accomplish this, however, an additional visible light source is required for aiming.
In addition, the module can be implemented as a surface mountable component.